/*
 * Copyright 2024 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.pajamas.protocol;

import java.util.Collection;
import java.util.Collections;
import java.util.EventObject;
import java.util.Objects;
import java.util.Set;
import java.util.stream.Collectors;

public interface EventHandler {
    static boolean isCollectionEmpty(Collection<?> collection) {
        return collection == null || collection.isEmpty();
    }

    /**
     * @return java.lang.Class<T>
     * @author william
     * @since 2024/1/21
     */
    Set<Class<? extends EventObject>> getCandidateEventObjectClasses();

    /**
     * @param eventObject eventObject
     * @return java.util.Set<java.lang.Class < ? extends java.util.EventObject>>
     * @author william
     * @since 2024/3/26
     */
    default Set<Class<? extends EventObject>> extractHintEventObjectClasses(EventObject eventObject) {
        Set<Class<? extends EventObject>> candidateEventObjectClasses = this.getCandidateEventObjectClasses();
        if (eventObject == null || isCollectionEmpty(candidateEventObjectClasses)) {
            return Collections.emptySet();
        }
        return candidateEventObjectClasses
                .stream()
                .filter(Objects::nonNull)
                .filter(aClass -> aClass.isAssignableFrom(eventObject.getClass()))
                .collect(Collectors.toSet());
    }

    default boolean skipHandle(EventObject eventObject) {
        Set<Class<? extends EventObject>> hintEventObjectClasses = this.extractHintEventObjectClasses(eventObject);
        return isCollectionEmpty(hintEventObjectClasses);
    }

    /**
     * @param eventObject eventObject
     * @author william
     * @since 2024/3/28
     */
    void handle(EventObject eventObject);

    /**
     * @param eventObject eventObject
     * @author william
     * @since 2024/3/28
     */
    default void tryHandle(EventObject eventObject) {
        if (!this.skipHandle(eventObject)) {
            this.handle(eventObject);
        }
    }
}
